Beverage making systems are known in which the beverage is made by inserting a capsule containing a particulate beverage making ingredient, such as ground coffee, into a beverage making station of a beverage making apparatus. The apparatus then injects water into the capsule, where the beverage making ingredient dissolves in, or infuses into, the water to form the beverage. The beverage flows out of the capsule through a suitable outlet, which may be simply an opening or perforation in the capsule, or it may comprise an outlet tube that pierces an outlet region of the capsule. The capsule may incorporate a filter to prevent passage of solid components such as coffee grounds out of the capsule. Beverage making systems of this general type are described for example in WO94/01344, EP-A-0512468 and EP-A-0468079 (all Nestle), in U.S. Pat. No. 5,840,189 and WO-A-0160220 (Keurig), in EP-A-0272922 (Kenco), in WO-A-2007093355 (Samar Technologies), in US-A-20110142996 (Kruger), EP-A-0710462 (Illycaffe), and in EP-A-0821906, US-A-20110000376 and US-A-20110027425 (Sara Lee).
GB-A-2121762, GB-A-2122881, EP-A-0179641, EP-A-0247841 and WO-A-9905044 describe capsule-based beverage preparation systems of the type that are now widely used and marketed by Mars Drinks under the registered trade mark FLAVIA®. An exemplary embodiment of a FLAVIA® capsule according to the state of the art is shown in FIGS. 1, 2a and 2b. Similar capsules are described in JP-A-4142266.
Referring to FIGS. 1, 2a and 2b, an exemplary FLAVIA®-type beverage preparation capsule 100 comprises front and back sheets 110, 112 of a liquid- and air-impermeable sheet material permanently bonded together around their top and side edges as described in more detail below. The front and back sheets are also bonded together along a bottom edge 120 of the capsule, but this bond is releasable under the effect of heat or pressure inside the capsule. For example, the bonding of the bottom edge 120 may be by means of a pressure-sensitive adhesive. Within the capsule 100 is a folded web of filter material 130 bonded to the inside walls of the front and back sheets. The web of filter material supports a beverage preparation ingredient 150, such as ground coffee or leaf tea. The capsule 100 further comprises a nozzle 140 having tubular bore 142. The nozzle is inserted into the top edge of the capsule and bonded in airtight fashion to the front and back sheets, the nozzle being flanged to assist in locating the capsule 100 correctly with a beverage preparation machine. The nozzle bore is initially sealed by a suitable airtight freshness barrier.
In use, the capsule 100 is introduced into a FLAVIA® dispensing machine, which comprises a clamp to grip the nozzle under the flange, and a hollow injector tube with a mechanism to insert the hollow injector tube into the nozzle bore, thereby piercing the freshness barrier. The dispensing machine further comprises a source of hot water and a pump to inject the hot water through the injector tube into the capsule. Upon introduction of the hot water through the injector tube and the nozzle bore, the beverage preparation ingredient 150 contained in the capsule 100 is mixed with the hot water and a beverage is brewed. The bottom seam 120 of the capsule 100 opens under the effect of heat and liquid pressure inside the capsule, and the beverage passes through the filter web 130 and the open bottom of the capsule and is collected in a receptacle located at a receptacle station situated directly below the capsule.
Referring to FIG. 2a, the sheet of web material 130 is folded to form a W in cross-section supporting the infusible beverage preparation ingredient 150. Upon introduction of liquid through the liquid conduct, the liquid pressure causes the apex 132 of the W to evert to provide a downwardly convex filter bed as shown in FIG. 2b. The eversion effect assists in the rupture of the pressure-sensitive seal of the bottom seam 120 to dispense a beverage brewed in the capsule. Further details and advantages of the everting filter webs may be found in EP-A-0179641. The FLAVIA® capsules and method provide beverages of superior quality, and furthermore provide the advantage of avoiding cross-contamination of the beverage preparation apparatus by successive beverages because the beverage does not contact any part of the apparatus after preparation.
Current beverage dispensing systems of the FLAVIA® type are adapted to prepare beverages by injection of hot water at only slightly elevated pressures, for example less than 1 bar gauge pressure. The capsules are not designed to operate at higher pressures. In particular, injection of water at higher pressures could cause the filter to separate from the pack. However, the preparation of certain premium beverages, in particular espresso coffee, requires water to be passed through the coffee bed at a pressure greater than 5 bar and up to about 20 bar. A need therefore remains for capsules, apparatus and beverage preparation methods for the preparation of espresso coffee and other high-pressure extraction beverages that also give the above-identified benefits of quality and no cross-contamination.
It is also known to brew individual portions of espresso coffee from individual capsules of ground coffee. The capsules typically contain a portion of ground coffee, tightly compacted in a capsule having a frustoconical or oblate spheroid shape and formed from air-and moisture-impermeable material. The capsule is inserted into a rigid, metal brewing chamber that is normally shaped to fit around the capsule tightly. The brewing chamber has a filter element in its base, means to pierce the underside of the capsule, and means to inject hot water at a pressure of 500-1500 kPa (5-15 bar) into the interior of the capsule to brew espresso coffee. Espresso coffee brewing capsules and systems of this type are described, for example, in WO93/17932 and WO94/02059.
A drawback of existing espresso brewing capsules is that they are adapted for use with conventional espresso machines that have a rigid brewing cavity dimensioned to receive a bed of coffee of specific dimensions and to apply the necessary pressure to such a bed of coffee. There is limited scope for varying the amount of coffee in the capsule, or for varying the degree of compaction of the coffee bed during brewing. A further drawback of the existing espresso systems is cross contamination between the successive brews, since the beverages exiting capsule passes through, and therefore contaminates, the base part of the brewing chamber.
EP-A-0521186 describes a capsule containing a compressed beverage brewing ingredient, such as ground coffee, for use in espresso-type machines. The capsule is deformable to assume the shape of the cavity of whichever espresso machine it is used in. This removes the need for a special adapter to adapt existing espresso machines to the exact shape and configuration of the capsule. Unfortunately, it also means that the coffee in the capsule may be insufficiently compacted for optimal espresso coffee brewing. The problem of cross-contamination by successive brews also exists for this configuration.
EP-A-0821906 describes methods of beverage brewing in which a vacuum pack containing a beverage brewing ingredient is placed in a clamp, hot water is injected into the vacuum pack through a hollow needle, and the brewed beverage is allowed to escape through a closing seam in the vacuum pack. The pack includes a movable plate opposite the closing seam of the vacuum pack that is used to compress the vacuum pack in the clamp before brewing. The plates making up the brewing cavity are rigid, flat plates. These plates cannot apply high pressure to squeeze the vacuum pack without risk of bursting the pack.
WO-A-0219875 describes an apparatus for the brewing of a beverage by transmission of an aqueous fluid through a capsule (capsule) containing a beverage brewing ingredient, said apparatus comprising: one or more injectors to inject the aqueous fluid into the capsule during said brewing; and a clamp for the capsule, said clamp comprising one or more members that are movable to open and close the clamp, said members having inner surfaces which in a closed position of the clamp define a cavity adapted to substantially enclose and support the capsule during said brewing and further adapted to define a beverage exit pathway in a lower part of the cavity, and wherein the inner surface of at least one clamp member comprises at least one deformable region mounted on a support that is movable while the clamp is in said closed position, whereby the shape of said cavity or said exit pathway can be changed while the clamp is in said closed position to provide a desired brewing configuration of the capsule. The capsule is suitably a capsule of the FLAVIA® type, optionally with modifications.
Channelling of liquid through the compressed bed of beverage preparation material during brewing may occur when preparing beverages using capsule-based (i.e. capsule-type) systems, especially where relatively high pressures are required such as in the preparation of espresso and espresso-type beverages. This channelling directs the liquid through preferred pathways in the compressed bed of beverage preparation material preventing uniform exposure of the beverage preparation material to the liquid and resulting in wasted beverage preparation material and a beverage having reduced concentration of dissolved or infused material. Channelling may occur in particular if the beverage ingredient is not uniformly and/or sufficiently compressed in the clamp prior to and during water injection.
Accordingly, a need remains for improved capsules, apparatus and methods for preparing beverages from capsules, especially at high pressures such as for producing espresso and espresso-type beverages from flexible capsule-type packs.